今天（2019-05-19）我无法连接到 VPN 内的内部资源——前一天还可以正常使用。这是因为 DNS 无法解析内部名称。
systemd-resolve 显示此
$ systemd-resolve --status
Global
DNSSEC NTA: 10.in-addr.arpa
16.172.in-addr.arpa
168.192.in-addr.arpa
17.172.in-addr.arpa
18.172.in-addr.arpa
19.172.in-addr.arpa
20.172.in-addr.arpa
21.172.in-addr.arpa
22.172.in-addr.arpa
23.172.in-addr.arpa
24.172.in-addr.arpa
25.172.in-addr.arpa
26.172.in-addr.arpa
27.172.in-addr.arpa
28.172.in-addr.arpa
29.172.in-addr.arpa
30.172.in-addr.arpa
31.172.in-addr.arpa
corp
d.f.ip6.arpa
home
internal
intranet
lan
local
private
test
Link 4 (vpn0)
Current Scopes: none
LLMNR setting: yes
MulticastDNS setting: no
DNSSEC setting: no
DNSSEC supported: no
Link 3 (docker0)
Current Scopes: none
LLMNR setting: yes
MulticastDNS setting: no
DNSSEC setting: no
DNSSEC supported: no
Link 2 (enp3s0)
Current Scopes: DNS
LLMNR setting: yes
MulticastDNS setting: no
DNSSEC setting: no
DNSSEC supported: no
DNS Servers: 192.168.1.254
fe80::1
DNS Domain: ~.
会是什么问题？VPN 问题？Ubuntu 更新？我昨天更新了一些东西，甚至不关心具体更新了什么。
Ubuntu 18.04 BTW。默认 IPv4 参数：DHCP 等。
UPD 看起来 DNS 服务器在这里。这又是 systemd-resolve 的问题：
… NetworkManager[1015]: <info> [1558277941.8897] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",0]: VPN connection: (IP Config Get) reply received.
… NetworkManager[1015]: <info> [1558277941.8915] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: VPN connection: (IP4 Config Get) reply received
… NetworkManager[1015]: <info> [1558277941.8922] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: VPN Gateway: ★★★.★★★.★★★.★★
… NetworkManager[1015]: <info> [1558277941.8922] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Tunnel Device: "vpn0"
… NetworkManager[1015]: <info> [1558277941.8922] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: IPv4 configuration:
… NetworkManager[1015]: <info> [1558277941.8922] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Internal Address: 10.5.0.81
… NetworkManager[1015]: <info> [1558277941.8922] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Internal Prefix: 24
… NetworkManager[1015]: <info> [1558277941.8922] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Internal Point-to-Point Address: 10.5.0.81
… NetworkManager[1015]: <info> [1558277941.8922] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.121.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.1.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.200.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.90.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.136.156.0/26 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 62.76.112.14/32 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 62.76.112.20/32 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.5.0.0/24 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 62.76.112.15/32 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 62.76.112.13/32 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 172.22.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 172.21.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8923] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.160.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8924] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 192.168.100.0/24 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8924] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 172.20.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8924] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.20.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.140.1.0/24 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.130.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.7.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.110.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.80.1.0/24 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.120.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.100.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.150.1.0/24 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.170.0.0/16 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Static Route: 10.5.0.0/24 Next Hop: 0.0.0.0
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Internal DNS: 10.110.1.2
… NetworkManager[1015]: <info> [1558277941.8925] vpn-connection[0x5647781d64c0,e7c29208-dec3-4b54-969f-6ef43b29a502,"Job",4:(vpn0)]: Data: Internal DNS: 10.100.1.3